• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.99-105
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• 2018

This paper proposes multiple access method for smart doorlock system using VLC(Visible Light Communication) with color grid modulation method. The proposed method is to connect multiple visible light signals using color grid modulation method in order to recognize and authenticate multiple users accessing doorlock. In order to enable visible light multiple access with existing infrastructure, the symbol energy interval of signal should be maximized. Thus, performance of system in VLC channel is measured by modulating symbols based on the proposed method. We confirm the actual channel test results of the modulated signal to implement doorlock system that recognizes the number of multiple access users.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.3
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• pp.214-221
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• 2021

SiC MOSFETs require a faster and more reliable short-circuit protection circuit than conventional methods due to narrow short-circuit withstand times. Therefore, this research proposes a short-circuit protection circuit using a current-sensing circuit based on Rogowski coil. The method of designing the current-sensing circuit, which is a component of the proposed circuit, is presented first. The integrator and input/output filter that compose the current-sensing circuit are designed to have a wide bandwidth for accurately measuring short-circuit currents with high di/dt. The precision of the designed sensing circuit is verified on a double pulse test (DPT). In addition, the sensing accuracy according to the bandwidth of the filters and the number of turns of the Rogowski coil is analyzed. Next, the entire short-circuit protection circuit with the current-sensing circuit is designed in consideration of the fast short-circuit shutdown time. To verify the performance of this circuit, a short-circuit test is conducted for two cases of short-circuit conditions that can occur in the half-bridge structure. Finally, the short-circuit shutdown time is measured to confirm the suitability of the proposed protection circuit for the SiC MOSFET short-circuit protection.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.10
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• pp.1469-1476
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• 2022

Recently, many researches have been conducted to estimate blood pressure using ECG(Electrocardiogram) and PPG(Photoplentysmography) signals. In this paper, we designed and implemented a mobile system to monitor blood pressure in real time by using 1-D convolutional neural networks. The proposed model consists of deep 11 layers which can learn to extract various features of ECG and PPG signals. The simulation results show that the more the number of convolutional kernels the learned neural network has, the more detailed characteristics of ECG and PPG signals resulted in better performance with reduced mean square error compared to linear regression model. With receiving measurement signals from wearable ECG and PPG sensor devices attached to the body, the developed system receives measurement data transmitted through Bluetooth communication from the devices, estimates systolic and diastolic blood pressure values using a learned model and displays its graph in real time.

• Computers and Concrete
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• v.29 no.3
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• pp.187-199
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• 2022

The usability of waste materials as raw materials is necessary for sustainable production. This study investigates the effects of different powder materials used to replace cement (0%, 5% and 10%) and standard sand (0%, 20% and 30%) (basalt, limestone, and dolomite) on the compressive strength (f_c), flexural strength (f_r), and ultrasonic pulse velocity (UPV) of mortars exposed to freeze-thaw cycles (56, 86, 126, 186 and 226 cycles). Furthermore, the usability of artificial intelligence models is compared, and the prediction accuracy of the outputs is examined according to the inputs (powder type, replacement ratio, and the number of cycles). The results show that the variability of the outputs was significantly high under the freeze-thaw effect in mortars produced with waste powder instead of those produced with cement and with standard sand. The highest prediction accuracy for all outputs was obtained using the adaptive-network-based fuzzy inference system model. The significantly high prediction accuracy was obtained for the UPV, f_c, and f_r of mortars produced using waste powders instead of standard sand (R² of UPV, f_c and f_f is 0.931, 0.759 and 0.825 respectively), when under the freeze-thaw effect. However, for the mortars produced using waste powders instead of cement, the prediction accuracy of UPV was significantly high (R²=0.889) but the prediction accuracy of f_c and f_r was low (R²f_c=0.612 and R²f_f=0.334).

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.22-22
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• 2003

This study was conducted to determine effects of polyvinyl alcohol (PVA), fetal bovine serum (FBS) and bovine serum albumin (BSA) on blastocoel formation, cell number, apoptosis and apoptosis-related gene expression of porcine diploid parthenotes developing in vitro. Embryos were collected from 2-cell or late 4-cell diploid parthenotes that activated with electro pulse, and in vitro cultured in the NCSU 23 medium supplemented without or with 0.1% PVA, 10% FBS or 0.4% BSA for day 7. The morphological analysis of apoptosis in embryos was carried out using propidium iodide staining and terminal deoxynucleotidyl transferase mediated dUTP nick end labeling. The expressions of Bcl-xL, Bak and P53 in blastocyst stage parthenotes and in vivo-derived blastocysts were determined using semiquantitative RT-PCR. The addition of 0.4% BSA to the culture medium enhanced the development of 2- or late 4-cell stage parthenotes to the blastocysts stage (P < 0.01) while FBS decreased the incidence of blastocoel formation. FBS also reduced cell numbers of blastocysts developed from both 2- (P < 0.001) and late 4-cell (P < 0.05) embryos and increased percentage of apoptosis in the blastocysts (P < 0.001). The relative abundance of Bcl-xL mRNA in diploid parthenotes cultured from 2-cell stage in the presence of BSA is similar with that in in vivo derived embryos, but is significantly higher than in parthenotes cultured with FBS, PVA or none protein supplement control. Bak mRNA showed a significant increase at the blastocyst stage in FBS supplement medium. This result suggests that apoptosis related gene expression is significantly affected by protein supplements, which may result in alteration of apoptosis and embryo viability of porcine embryos developing in vitro.

• Journal of agriculture & life science
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• v.50 no.2
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• pp.187-194
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• 2016

The purpose of this study was to analyze temperature distribution characteristics using a model swine housing for temperature sensor adjustable positioning and developed a sensor and controller embedded exhaust fans utilizing ICT fusion technology for windowless swine housing. Temperature measured by the sensor attached on the exhaust fan was also determined that there is no problem, the temperature is located in the upper fan given the measured errors shown in the 1℃ temperature difference between the lower temperature than the other positions in the model swine housing. The performance of the exhaust fan at maximum output was found to be 1920rpm, air flow rate 125㎥/min. When the open area ratio of 70% one proper air volume of the exhaust fan was found to be 75㎥/min, 60pa. Maximum efficiency in all of the output of the exhaust fan is exhibited at about 70% open area ratio of the damper. The number of revolution of the exhaust fan was 1920rpm when the output was a maximum of 100%. AC output phase of the pulse duty ratio change of the controller was shown to change without delay. It was determined that the instant fan speed control is possible.

• Clinical Pain
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• v.18 no.2
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• pp.65-69
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• 2019

Objective: This study aims to evaluate the efficacy of high-voltage microcurrent therapy in patients with herniated lumbar disc (HLD) presenting radicular or back pain. Method: This is a retrospective study with 33 patients who are complaining pain with HLD findings on magnetic resonance image. Microcurrent therapy was applied to leg or paralumbar area. Treatment was conducted for seven minutes with 250~1000 uA intensity as high as the patients could tolerate via stimulating probe with roller type and the frequency was 60 Hz with a sine wave pulse. The visual analogue scale (VAS) was measured just before and after the treatment. Results: The degree of pain reduction (△VAS) was 1.6 points after treatment on average. The △VAS according to the diagnosis, stenosis, dermatome area, medication, pain site and caudal epidural block was not statistically significant. However, the △VAS according to the number of treatments (< 3, ≥ 3 times) showed a statistically significant difference (p=0.04). Conclusion: High-voltage microcurrent therapy may help reduce lumbar or lumbosacral radiating pain after the procedure. The effect was better when microcurrent was applied three times or more. This result suggests that the microcurrent would have cumulative effect on reducing radicular or back pain in patients with HLD.

• Restorative Dentistry and Endodontics
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• v.27 no.2
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• pp.158-174
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• 2002

The aim of this study was to investigate the effect of light irradiation modes on polymerization shrinkage, degree of cure and microleakage of a composite resin. VIP$^{TM}$ (Bisco Dental Products, Schaumburg, IL, USA) and Optilux 501$^{TM}$ (Demetron/Kerr, Danbury, CT, USA) were used for curing Filtek$^{TM}$ Z-250 (3M Dental Products, St. Paul., MN, USA) composite resin using following irradiation modes: VIP$^{TM}$ (Bisco) 200mW/$\textrm{cm}^2$ (V2), 400mW/$\textrm{cm}^2$ (V4), 600mW/$\textrm{cm}^2$ (V6), Pulse-delay (200 mW/$\textrm{cm}^2$ 3 seconds, 5 minutes wait, 600mW/$\textrm{cm}^2$ 30seconds, VPD) and Optilux 501$^{TM}$ (Demetron/Kerr) C-mode (OC), R-mode (OR). Linear polymerization shrinkage of the composite specimens were measured using Linometer (R&B, Daejeon, Korea) for 90 seconds for V2, V4, V6, OC, OR groups and for up to 363 seconds for VPD group (n=10, each). Degree of conversion was measured using FTIR spectrometer (IFS 120 HR, Bruker Karlsruhe, Germany) at the bottom surface of 2 mm thick composite specimens V2, Y4, V6, OC groups were measured separately at five irradiation times (5, 10, 20, 40, 60 seconds) and OR, VPD groups were measured in the above mentioned irradiation modes (n=5 each). Microhardness was measured using Digital microhardness tester (FM7, Future-Tech Co., Tokyo, Japan) at the top and bottom surfaces of 2mm thick composite specimens after exposure to the same irradiation modes as the test of degree of conversion(n=3, each). For the microleakage test, class V cavities were prepared on the distal surface of the ninety extracted human third molars. The cavities were restored with one of the following irradiation modes : V2/60 seconds, V4/40 seconds, V6/30 seconds, VPD , OC and OR. Microleakage was assessed by dye penetration along enamel and dentin margins of cavities. Mean polymerization shrinkage, mean degree of conversion and mean microhardness values for all groups at each time were analyzed using one-way ANOVA and Duncan's multiple range test, and using chi-square test far microleakage values. The results were as follows : . Polymerization shrinkage was increased with higher light intensity in groups using VIP$^{TM}$ (Bisco) : the highest with 600mW/$\textrm{cm}^2$, followed by Pulse-delay, 400mW/$\textrm{cm}^2$ and 200mW/$\textrm{cm}^2$ groups, The degree of polymerization shrinkage was higher with Continuous mode than with Ramp mode in groups using Optilux 501$^{TM}$ (Demetron/Kerr). . Degree of conversion and microhardness values were higher with higher light intensity. The final degree of conversion was in the range of 44.7 to 54.98% and the final microhardness value in the range of 34.10 to 56.30. . Microleakage was greater in dentin margin than in enamel margin. Higher light intensity showed more microleakage in dentin margin in groups using VIP$^{TM}$ (Bisco). The microleakage was the lowest with Continuous mode in enamel margin and with Ramp mode in dentin margin when Optilux 501$^{TM}$ (Demetron/Kerr) was used.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.3
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• pp.243-250
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• 1981

Soybean, azuki-bean and mungbean were cultivated at different growing conditions, May 10, June 9, July 9 seeding, and May 10 seeding-short day treatment, to investigate the distribution of flowering date and the variation of pod/flower ratio. The growth habit type of the soybean variety used was determinate, but the azuki-bean and mungbean varieties used showed indeterminate growth habit. The pod/flower ratio ranged 38 to 48% for soybean, 23 to 34% for azuki-bean and 46 to 60% for mungbean along with growing conditions. Flower abscission for soybean and mungbean, and pod abscission for azuki-bean affected more on the number of matured pods. Soybean showed once full blooming period, but azuki-bean and mungbean showed two or three times full blooming period except July 9 seeding plot through the whole growing period. Flowers bloomed just after every full blooming period showed lower value of pod/flower ratio and higher pod/flower ratio was obtained from flowers bloomed before or far after full blooming at plots seeded May 10 and June 9 in three pulse crops. Most full blooming period of soybean coincided within 5 days near the terminal leaf appearance date, and number of flowers bloomed before terminal leaf expansion and matured pods from these flowers were major in every soybean plant at all growing codition plots. No relations were found between terminal leaf appearance and flowering or pod setting patterns of azuki-bean and mungbean.

• Korean Journal of Remote Sensing
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• v.36 no.2_2
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• pp.351-363
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• 2020

It is well known that alluvial sediment located in coastal region has been easily affected by geohazard like ground subsidence, marine or meteorological disasters which threaten invaluable lives and properties. The subsidence is a sinking of the ground due to underground material movement that mostly related to soil compaction by water extraction. Thus, continuous monitoring is essential to protect possible damage from the ground subsidence in the coastal region. Radar interferometric application has been widely used to estimate surface displacement from phase information of synthetic aperture radar (SAR). Thanks to advanced SAR technique like the Small BAseline Subset (SBAS), a time-series of surface displacement could be successfully calculated with a large amount of SAR observations (>20). Because the ALOS-2 PALSAR-2 L-band observations maintain higher coherence compared with other shorter wavelength like X- or C-band, it has been regarded as one of the best resources for Earth science. However, the number of ALOS-2 PALSAR-2 observations might be not enough for the SBAS application due to its global monitoring observation scenario. Unfortunately, the number of the ALOS-2 PALSAR-2 Stripmap images in area of our interest, Busan which located in the Southeastern Korea, is only 11 which is insufficient to apply the SBAS time-series analysis. Although it is common that the radar interferometry utilizes multiple SAR images collected from same acquisition mode, it has been reported that the ALOS-2 PALSAR-2 Stripmap-ScanSAR interferometric application could be possible under specific acquisition mode. In case that we can apply the Stripmap-ScanSAR interferometry with the other 18 ScanSAR observations over Busan, an enhanced time-series surface displacement with better temporal resolution could be estimated. In this study, we evaluated feasibility of the ALOS-2 PALSAR-2 Stripmap-ScanSAR interferometric application using Gamma software considering differences of chirp bandwidth and pulse repetition frequency (PRF) between two acquisition modes. In addition, we analyzed the interferograms with respect to spectral shift of radar carrier frequency and common band filtering. Even though it shows similar level of coherence regardless of spectral shift in the radar carrier frequency, we found periodic spectral noises in azimuth direction and significant degradation of coherence in azimuth direction after common band filtering. Therefore, the characteristics of spectral bandwidth in the range and azimuth direction should be considered cautiously for the ALOS-2 PALSAR-2 Stripmap-ScanSAR interferometry.